Phone-hacking scandal: Andy Coulson under fresh attack

Evidence contained in outline for book which was planned by private investigator at the centre of the affair, Glenn Mulcaire

David Cameron and Andy Coulson at The Millies - A Night for Heroes Awards 2009, at the Imperial War Museum. Photograph: David Fisher / Rex Features David Fisher / Rex Features/David Fisher / Rex Features

David Cameron's close adviser, Andy Coulson, has come under fresh attack after the disclosure of new evidence of the News of the World's role in the illegal interception of the royal household's voicemail messages during his time as editor.

The evidence is in the outline for a book planned by the private investigator at the centre of the affair, Glenn Mulcaire. The outline was written before Mulcaire signed a deal with the paper which stopped the book's publication and gagged him from speaking about the scandal.

The outline directly contradicts the News of the World's claim that Mulcaire broke the law without the paper's knowledge or consent. It describes an unnamed editorial executive at the News of the World commissioning Mulcaire to intercept the royal messages and claims that the paper pressed him to continue with the interceptions when he tried to stop.

It also refers to an unnamed person approaching him to "change his story", although it does not say whether this was an employee of the News of the World. Coulson has insisted that he does not remember any of his journalists being involved in breaking the law.

Labour's business secretary, Peter Mandelson, said: "The idea that as editor of the News of the World Andy Coulson was not aware of this activity beggars belief. If the election in less than a week goes the Tories' way, we would see this man taking on a major role in the British government. People should think long and hard before considering voting Conservative."

The Lib Dems' home affairs spokesman, Chris Huhne, said: "Coulson is in this up to his neck and it is shocking that Cameron continues to employ someone with his history of presiding over skulduggery. It was always an astonishing lapse of judgment to hire someone who was either complicit in criminal activity or the most incompetent editor in Fleet Street's modern history."

Mulcaire produced the outline for the book with the help of friends after he and the News of the World's royal correspondent, Clive Goodman, were arrested in August 2006 following an inquiry by Scotland Yard into complaints from Buckingham Palace. The outline describes the proposed book as "an inside look at how the murky world of tabloid journalism decided to tap the phones of the royal household".

The outline does not name names, but Coulson's newspaper appears repeatedly as the instigator of the attack on the royal household's messages. Mulcaire was on contract for the News of the World as a private investigator from 2001.

A summary of one chapter describes how the plan to intercept royal messages began with a call from an editorial executive at the paper. Mulcaire implies he was reluctant to agree, but adds: "I was under contract, so there was little choice."

That reluctance to accept the News of the World's plan becomes a running theme. In the summary of the chapter about the operation to intercept the royal phones, Mulcaire refers to pressure being placed on him and says: "I didn't want to do the assignment. Anything that involves the royals or the establishment has me twitchy straight away, but I was under contract and you just have to switch off about the specifics and be professional."

A source who advised Mulcaire on the writing of the outline says that, having intercepted messages for the paper for several months, Mulcaire tried to stop in November 2005 after the News of the World published a story about Prince William needing a knee operation which clearly had come from his voicemail.

The outline suggests that he was pressed to continue by Clive Goodman, backed up with the threat that he would lose his contract if he refused: "We had had the security breach. I wanted to stop there. I knew any more would be pushing our luck, but Goodman was hungry.

"In the end, I was given no real choice. He knew I could give him access to a cash cow. One call from me, and he could get a royal exclusive. But most importantly, he knew I was under contract. I was told in no uncertain terms: 'Stop now and you will never work in the media again'. What choice did that give me? My loyalty cost me."

The outline suggests that there was a successful move to persuade Mulcaire not to disclose any of this when he came to court and reveals that the proposed book was intending to name the person "who approached him to change his story".

Mulcaire and Goodman pleaded guilty and were jailed in January 2007 at a court hearing in which no evidence was produced of the News of the World's involvement in any illegal activity.

Since then the Guardian has disclosed that other journalists from the News of the World were involved with Mulcaire's activities, and that Mulcaire was one of four private investigators who used illegal methods to gather information for stories while Coulson was deputy editor or editor of the News of the World.

One of them was hired from his budget even though he had a track record of blackmail and the corruption of police officers. Coulson says he has no recollection of any of his journalists breaking any law.

In its inquiry into the affair, the House of Commons media select committee suggested that witnesses from the News of the World had suffered from "collective amnesia". The paper has paid out some £2m to suppress court actions brought by two confirmed victims, Gordon Taylor of the Professional Footballers' Association, and Max Clifford, the celebrity PR agent. It also paid an unknown amount to Goodman and Mulcaire in deals which required them not to speak about the issue. Various other alleged victims from the worlds of politics, sport and entertainment are believed to be preparing to sue.